THP54 　ポスター③　 8月31日 14号館1444教室 13:30-15:30

The performance of large and medium grain niobium cavities with high-Q/G surface treatment

○Hayato Araki, Hayato Ito, Ashish Kumar, Kensei Umemori (KEK)

Niobium material with small crystal grains, called "Fine Grain", is generally used for fabricating SRF cavities. Our group have been working on cavity fabrication and performance measurement using new materials called "Large Grain" and "Medium Grain," which omit some of the fabrication processes of FG materials, and are expected to reduce fabrication costs without sacrificing cavity performance. On the other hands, several surface treatments for 1.3 GHz cavities have been reported in recent years that achieve higher performance than the ILC standard treatment. In particular, two surface treatments, "two-step baking" and "furnace baking", are expected to provide both low loss (high-Q) and high gradient (high-G) performance, but these discussions are currently focused on cavities in standard FG materials. In this presentation, we will report on the results of performance measurements performed so far at KEK on LG and MG cavities with two-step baking and furnace baking surface treatments.